Study On Synthesis And Properties Of Nano-Inorganic Additives In Lubrication Oil

In recent years, the demand has been strong for improvement of the fueleconomy of automobile engines. From the standpoint of engine oil formulations, agreat deal of research effort has been devoted to the development of effectivefuel-saving type lubricants and friction reduction by friction modifiers.Simultaneously, modifying the antiwear and lubricating property of material hasan important effect on the saving of resources and environmental protection. It notonly satisfies the tendency of higher speed, heavier load and higher accuracy ofthe machine demanded by modern scientific technology, but also lengthens thelife of the machine. In this paper, we have focused on the control of the size andshape of nanoparticles by developing effective synthetic techniques ofmolybdenum disulfide nanoparticles and zinc borate nanoparticles. There aremany valuable and innovative conclusions through systemic studies.Molybdenum disulfide (MoS2) is one of the traditionally representative solidlubricating materials and has been widely accepted as coatings and additive inlubrication oil. In this paper, we reported a route for synthesis of MoS2 nanorodsby means of redox reaction in the aqueous solution at 90℃. It had been found thatthe as-prepared materials had a rod–like shape with lengths of 50 nm-150 nm anddiameters of 20 nm-40 nm. The influences of solution acidity on the samples ofpurity, possible reaction route, the influences of surfactant on the formation ofMoS2 nanorods and the growth mechanism of MoS2 nanorods were discussed,respectively. The pure MoS2 were obtained when the concentration of HCl wasfrom 0.8mol/l to 1.0mol/l. Moreover, the friction coefficient of the base oil wasdecreased by the addition of MoS2 nanorods.At the same time, the MoS2 nanospheres were successfully synthesizedthrough a facile and an inexpensive hydrothermal synthetic process. Themorphology, composition, diameter, size and size distribution, differential thermaland weight loss of MoS2 particles were measured by X-ray diffraction (XRD),transmission electron microscopy (TEM) equipped with an energy-dispersiveX-ray spectrometer (EDS), Zetasizer analyzer and differential thermal andthermogravimetric analysis (DTA-TG) in air. It had been found that theas-prepared materials displayed sphere morphology with mean diameters of 30nm. The possible reaction route, the different pH values of the solution onsynthesis of pure MoS2 and the reaction temperature on the size of MoS2 werediscussed. Thus MoS2 nanospheres turned sliding friction into partially rollingfriction, which greatly decreased the friction coefficient of the base oil.As borate salts, zinc borate has been the subject of significant research forapplications including a wear resistance and additive in lubrication oil, a polymeradditive which serves as a fire retardant synergist, char promoter, anti-arcing agent,a preservative in wood composites, smoke and afterglow suppressant additive.The crystal zinc borate (2ZnO 3B2 O3 3H2O) nanospheres were successfullysynthesized by water-in-oil microemulsion. It had been found that the as-preparedmaterials display sphere morphology with mean diameters of 17 nm (w=5). Thedehydration temperature process started about 208.5℃ and reached weight lossof 13. 962% corresponds to the loss of three molar equivalents of water andformed 2ZnO 3B2 O3. The dehydration reaction of changes in molar enthalpy was132.04kJ mol-1. The procedural variables could affect the shape of the DTA curves.An increase in the heating rate caused an increase in the peak temperature.The crystal and hydrophobic zinc borate (Zn2 B OB6 11 3H2O) nanosheets weresuccessfully prepared by a wet method using Na2B4O7 10H 2 O and ZnSO4 7H2BOas raw materials in situ aqueous solution, and oleic acid as the modifying surfaceagent. Surface energy of zinc borate nanoparticles was reduced, and thecomparability between zinc borate nanoparticles and the base oil as well aspolymers was enhanced. Oleic acid is a cheap unsaturation organic acid includingcarboxyl and C=C double bonds functional groups. It had been found that theas-prepared materials displayed nanosheet morphology with average diametersfrom 100 nm to 500 nm and the thicknesses about 30 nm. The reaction parametersincluding the pH of the solution, the mole ratios of Na 2B O 10HB4 7 2O andZnSO4 7H2O and the reaction time played important roles on the formation of thehydrophobic zinc borate. Oleic acid was bonded to zinc borate surface with acovalent bond between carboxyl functional groups and hydroxy groups on thesurface of zinc borate nanoparticles. The presence of the oleic acid on the surfacemodified zinc borate was confirmed by the thermogravimetric analysis and FTIRspectroscopy. The relative contact angle of the hydrophobic zinc borate wasincreased to 132°. Moreover, the friction coefficient of the base oil was decreasedby the addition of hydrophobic zinc borate nanosheets and the fluctuation of thefriction coefficient was very small.In recent years, advanced materials derived from core/shell compositeparticles are of extensive scientific and technological interests due to the ability topotential their properties with developments in nanotechnology. In this regard,nanoparticles with core/shell morphologies represent a new type of constructionalunit consisting of two dissimilar compositional and structural domains. Suchmaterials should have enhanced physical and chemical properties and a broaderrange of applications than their single-component counterparts. The structure, size,and composition of these particles can be easily altered in a controllable way totailor their magnetic, optical, mechanical, thermal, electrical, tribological andcatalytic properties. The core/shell morphology can be used as a precursor form toproduce hollow spheres or to lower the cost of precious materials by coating themon inexpensive cores. Core/shell materials can also be used to protect medicinesor other materials from dissolution or hydrolysis and to strengthen polymericmaterials. To the best of our knowledge, the synthesis of silica/zinc boratecore/shell nanoparticles has not been reported up to now. Our method involvedthe direct synthesis of silica nanospheres and a thin zinc borate coating was thendeposited onto the silica surface through a self-assembly process. The obtainedSiO2 /Zn5B OB4 11 core/shell nanospheres had perfect spherical shape with narrowsize distribution (average diameters 50nm), i.e., the cores with mean diameters of40 nm and the shells with an average thickness of 5 nm, monodisperse andsmooth surface. The cores were amorphous phase SiO2 and the shells werepolycrystalline phase Zn5 B4O11B. Moreover, the friction coefficient of the base oilwas decreased by the addition of SiO2 /Zn5 B OB4 11 core/shell nanospheres.